1. Field of the Disclosure
The present disclosure relates to a bi-directional data transmission.
2. Discussion of the Background Art
In communication systems, it is often necessary to transfer data in both directions over the same physical communication link. In communication systems with such bi-directional communication links, the communication terminals provided at each end of a bi-directional communication link comprise each a transmitter and a receiver associated to each other for transmitting and receiving data respectively.
Transferring data in both directions over the same physical line necessitates separating the data flow of the both directions; it is thus necessary to prevent a receiver from mixing of a signal transmitted by the associated transmitter and a signal received from another transmitter.
To avoid a signal mixing, it is well known to establish a method, wherein a transmitter is only allowed to transmit data if no data is received at the same time. However, due to a transmission time depending on the length of the line, a corresponding waiting time, also referred to as roundtrip time, has to be additionally taken into account.
Integrated circuits with high data rates, also referred to as high speed integrated circuits and further also generally referred to as device under test -DUT., face the problem that an automatic test equipment -ATE- for testing such circuits needs to take into account increasing roundtrip times, as for high-speed testing the data direction between ATE and DUT is changing frequently. Therefore, to avoid the impact of roundtrip times, U.S. Pat. No. 6,064,242 describes a test setup wherein a driver and a comparator in an ATE are separated and each connected over independent lines to a device under test.
In the article “An 8-Gb-/s Simultaneous Bidirectional Link With On-Die Waveform Capture”, IEEE Journal of Solid-State Circuits, Vol. 38, No. 12, December 2003, a method is disclosed that allows for simultaneously transmitting and receiving digital data over a physical link. According to this article, a comparator threshold at a receiver for detecting a received digital data stream is switched according to the actual value of a transmitted digital data stream.